The data on the 'coordination number' n and on the nearest-neighbor distance R-nn in liquid CF4 within a broad range of experimental conditions were obtained by the analysis of the profiles of (v(1) + v(3)) and of (v(3) + v(4)) IR-absorption bands. The pronounced linear increase on density of n was observed whereas value of R-nn = 4.40(5) Angstrom was practically invariable. We consider that the variation of vacancies number is mainly responsible for the change of the density of the liquid on the alteration of its thermodynamic conditions, and it is not due to a simple dilation or contraction of the medium. (C) 2003 Elsevier B.V. All rights reserved.